Stabilization of chlorinated hydrocarbons with 3-amino-2-methyl-butan-2-ol



; atent Ofiice Patented Aug. 13, 1957 STABHJZATIQN F CI EURINATEDHYDROCAR- BONS WITH 3-AMTNG-Z METHYL-BUTAN-Z-OL Gordon E. Cole, In, Cos(Job, Conn, assignor to Air Reduction Company, Incorporated, New York,N. Y., a corporation of New York No Drawing. Application August 16,1954, Serial No. 450,240

5 Claims. (Cl. 260-6525) This invention relates to the stabilization ofchlorinated hydrocarbons. More particularly, it relates to thestabilization of chlorinated hydrocarbon solvents such astrichlorethylene and perchlorethylene.

The chlorinated hydrocarbons find wide commercial application assolvents for greases and other organic materials. For example,chlorinated hydrocarbons are used extensively in degreasing metallicarticles, extracting caffein from cofiee, and in dry cleaning. Whilechlorinated solvents are recognized to be of great value for these andother purposes, their use is accompanied by a serious drawback. It isknown that when these chlorinated hydrocarbon solvents are exposed toheat, light, and air they decompose with the formation of substances,usually acidic products, with objectionable characteristics. It is alsoknown that this decomposition reaction is accelerated by the presence ofmetallic particles such as iron or aluminum. While the acidity developedis relatively small on a percentage basis, even such relatively smallamounts of acid substances can not be tolerated since the solventsnormally are shipped in metallic containers and come into contact withmetallic apparatus. In addition, the acidic materials are detrimental tofabrics and to many dyes. Furthermore, the amount of acidic materialspresent is cumulative, since these solvents are normally used over andover again.

Many attempts have heretofore been made to either prevent thedecomposition of chlorinated solvents or add chemical substances to suchsolvents to react with or neutralize the objectionable substances formedby the decomposition of such solvents. Since the chemical mechanism ofthis decomposition reaction is not definitely known, nor fullyunderstood, the ability of a material to elfectively stabilizechlorinated hydrocarbon solvents can only be established empirically.

It is an object of this invention to provide an efiective stabilizer forchlorinated hydrocarbons, such as trichlorethylene and perchlorethylene,which is effective in small concentrations, and which does not developan objectionable odor. Other objects will in part appear in, and in partbe obvious from, the following detailed description.

It has now been discovered that the compound, 3-amino-2-methyl-butan-2-ol, is particularly effective in stabilizingtrichlorethylene and perchlorethylene. This compound may be representedby the structural formula In general, the proportion of3-amino-2-methyl-butan- 2-ol added to the chlorinated solvent may rangefrom as low as about 0.01 percent by weight to about 1.0 percent byweight. The amount of stabilizer added will depend upon the particularsolvent to be stabilized, the intended use of the solvent composition,and the degree of stability desired.

For many applications it may be desirable to combine the3-amino-2-methyl-butan-2-ol with other stabilizers. For example, it maybe admixed with alkaline-reacting materials such as inorganicalkaline-earth oxides, e. g., calcium carbonate, or organic amines, e.g., pyridine or triethylamine, catechol or p-hydroxy tert.butylphenol;unsaturated materials such as diisobutylene; and pyrroles such asN-methyl pyrrole and pyrrole.

While the use of 3-amino-2-methyl-butan-2-ol is most eifective withtrichlorethylene and perchlorethylene, it may also be used to stabilizeother chlorohydrocarbons such as methylene chloride, chloroform, methylchloroform, ethylene dichloride, trichlorethane, vinylidene chloride,vinyl chloride and others.

The stabilizer of this invention, 3-arnino-2-methylbutan-Z-ol, may beprepared by reductively aminating 2- hydroxy-Z-methyl-3-butanone in thepresence of a Raney nickel catalyst and with an excess of ammonia at C.,and under an initial pressure of 1000 p. s. i. in the manner describedby Bergmann and Herman in the J. Applied Chem, vol. 3, pp. 42-48 (1953).

The process of stabilization comprises admixing a small but stabilizingamount, for instance 0.01 to 1.0 percent by weight, of3amino-2-methyl-butan-2-ol with the chlorinated hydrocarbon solvent. Forexample, a stabilized mixture of trichlorethylene may be made up byadding 0.1 percent by weight of 3-arnino-2-methylbutan-Z-ol to saidtrichlorethylene.

The term stabilize, in its various forms, as used in the foregoingspecification and the appended claims, is intended to refer to theinhibition of the decomposition reaction and/ or the neutralization ofany deleterious decomposition products.

What is claimed is:

l. A composition of matter comprising a chlorinated hydrocarbon solventselected from the group consisting of trichlorethylene andperchlorethylene and between about 0.01 percent to about 0.1 percent byweight of 3- amino-2-methyl-butan-2-ol.

2. A composition of matter comprising trichlorethylene and between about0.01 percent to about 0.1 percent by weight of3-amino2-methyl-butan-2-ol.

3. A composition of matter comprising perchlorethylene and between about0.01 percent to about 0.1 percent by weight of3-amino-2-methyl-butan-2-ol.

4. The process for stabilizing trichlorethylene which comprises admixingfrom about 0.01 percent to about 0.1 percent by weight of3-amino-2-methyl-butan-2-ol with said trichlorethylene.

5. The process for stabilizing perchlorethylene which comprises admixingfrom about 0.01 percent to about 0.1 percent by weight of3-amino-2-methyl-butan-2-ol with said perchlorethylene.

References Cited in the file of this patent UNITED STATES PATENTS2,371,644 Petering a a1. Mar. 20, 1945

1. A COMPOSITION OF MATTER COMPRISING A CHLORINATED HYDROCARBON SOLVENTSELECTED FROM THE GROUP CONSISTING OF TRICHLORETHYLENE ANDPERCHLORETHYLENE AND BETWEEN ABOUT 0.01 PERCENT TO ABOUT 0.1 PERCENT BYWEIGHT OF 3AMINO-2-METHYL-BUTAN-2-OL.